This invention relates generally to automotive emission control valves, such as exhaust gas recirculation (EGR) valves that are used in emission control systems of automotive vehicles with internal combustion engines (I.C.E.). More specifically, the invention relates to a valve seat for an EGR valve that achieves a characteristic flow of the exhaust gas.
In an EGR systems module (ESM) that includes an EGR valve, a transducer is used to measure a pressure differential across a valve orifice. This pressure differential is used to calculate exhaust gas flow through the EGR valve. In order to measure this pressure differential, static pressure ports are located upstream and downstream of the valve orifice.
The inventor of the claimed invention has discovered that a known ESM can exhibit a flow characteristic referred to as xe2x80x9ccurl back,xe2x80x9d which is illustrated in FIG. 1. Specifically, exhaust gas flow, which is measured as a function of the multiplication product of differential pressure (DP) and manifold absolute pressure (MAP), xe2x80x9ccurls backxe2x80x9d at the ends of the representative curves. Thus, there is not a unique correspondence between the multiplication product (DP*MAP) and flow through the valve. As illustrated in FIG. 1, there may be two or more different flow values that correspond to a single DP*MAP value. Since DP*MAP is used by an engine control unit (ECU) to determine if the EGR valve should be opened or closed, the xe2x80x9ccurl backxe2x80x9d characteristic of such a conventional EGR is a disadvantage. For example, the xe2x80x9ccurl backxe2x80x9d characteristic can cause the ECU to determine a decreasing flow condition even though the EGR valve is opening, i.e., DP*MAP is decreasing while flow and duty cycle are increasing.
Thus, it is believed that there is a need to eliminate the xe2x80x9ccurl backxe2x80x9d characteristic in exhaust flow through EGR valves.
The claimed invention provides an emission control valve assembly that comprises a valve body and a seat. The valve body has a passage that connects a first port to a second port. The passage has a first passage portion that extends from the first port along a first central axis, a second passage portion that extends from the second port along a second central axis, and a third passage portion that extends along a third central axis. The third passage portion connects the first and second passage portions at respective first and second points along the third axis. The seat extends along the third central axis and is located between the first and second points. The seat has a first rim that lies in a first plane oriented orthogonally with respect to the third central axis, and a second rim that lies in a second plane oriented obliquely with respect to the third central axis.
The claimed invention also provides an exhaust gas recirculation passage for an internal combustion engine. The passage comprises an inlet, an outlet, and an orifice between the inlet and the outlet. The orifice defines a portion of the passage and extends along a central axis between a first rim and a second rim. The first rim lies in a first plane oriented orthogonally with respect to the central axis, and the second rim lies in a second plane oriented obliquely with respect to the central axis.
The claimed invention further provides a method of recirculating an exhaust gas flow from an exhaust port to an intake port of an internal combustion engine. The method comprises providing a valve regulating the exhaust gas flow. The valve includes a body defining a passage between an inlet port and an outlet port. The body includes a seat and a valve. The seat is disposed along the passage and has a rim providing an outlet for the exhaust gas flow through the seat. The rim lies in a plane that is oriented obliquely with respect to a first axis. The valve reciprocates along the first axis with respect to the seat. The valve reciprocates between a first configuration that prohibits the exhaust gases from flow through the seat, and a second configuration that permits the exhaust gas to flow through the seat. And flowing the exhaust gas flow through the seat such that a multiplication product of manifold absolute pressure and differential pressure on opposite sides of the valve increases as the exhaust gas flow increases.
The claimed invention yet further provides a method of recirculating exhaust gas flow from an exhaust port to an intake port of an internal combustion engine. The method comprises providing a valve interposed between the exhaust and intake ports; measuring a differential pressure on opposite sides of the valve; measuring a manifold absolute pressure in the intake manifold; calculating a multiplication product of the differential pressure and the manifold absolute pressure; and determining a unique value of the exhaust gas flow for every multiplication product.